The questions and answers below are intended as a guideline in the use of our product NOGALL. If you need more technical answers please feel free to use our Technical enquiry form at the bottom of this page.
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Crown gall is a cancerous disease of many dicotyledonous plants that is caused by four main groups of soil and plant-inhabiting, ubiquitous agrobacteria: Agrobacterium tumefaciens (biovar1 group), Rhizobium rhizogenes (formerly Agrobacterium radiobacter and A. rhizogenes)(biovar2 group), A. vitis (biovar3 group) and R. rubi (formerly A. rubi).
These bacteria are present in most agricultural soils and cause disease that affect plants in nurseries, landscapes, vineyards and orchards worldwide. Shrubs, ornamental flowering trees, fruit trees in temperate to tropical areas, tubers, grapevines, tobacco, annuals and members of Coniferae are just some of the plants affected by crown gall. Infections occur in plant wounds caused by transplanting, cultivation, grafting, taking cuttings, pruning, etc…
Other wounds caused by insects, animals, or people can also serve as sites for infection. Pathogenic agrobacteria are attracted to chemical compounds (e.g. acetosyringone) leaking from wound sites where they colonise and firmly attach to injured plant cells during a three phase process. Once attached, the agrobacteria can transfer part of its T-DNA from its tumour inducing plasmid (Ti) into the DNA of the plant. The T-DNA, once inside the plant cell DNA, encodes for production of plant hormones (auxin and cytokinins) and carbon-nitrogen compounds called opines.
Opines become food for the disease-causing agrobacteria that can then colonise on and around the outside of the developing gall tissue. Galls, caused by the overproduction of plant hormones, are typically located on the crown of the plant at or below the soil surface but can also occur in the root zone, at the base of cuttings, in grafts, on stems, canes, vines or leaves.
Galls vary considerably in size from 5mm to 30cm or more in diameter. Young galls are soft on the surface and have a light, tan-coloured, frosty appearance. As the galls become older they grow darker, turning almost black, and are usually hard and woody. Galls interfere with the movement of water and nutrients between roots and leaves.
Affected plants may be stunted, produce small chlorotic leaves and may become more sensitive to environmental stresses such as winter injury. Fruit trees infected with crown gall produce lower yields with variable fruit set, size and quality. In severe conditions crown gall can weaken or kill the host plant. Losses to the nursery industry can be particularly severe because plants with crown gall must be culled.
NOGALL is a wettable powder inoculant containing a pure culture of the bacterium Rhizobium rhizogenes (formerly Agrobacterium radiobacter), strain K1026. It is used as a treatment for the biological control of certain pathogenic agrobacteria that cause crown gall disease on targeted horticultural and ornamental plants. NOGALL is a preventative, not curative, treatment against crown gall disease. NOGALL was first sold to plant nurseries in Australia in 1975 and later commercialised as a biopesticide in Turkey and the USA.
NOGALL with K1026 is effective against most crown gall pathogens, particularly ones able to catabolise the opines nopaline and agrocinopine A, affecting stone fruit trees, (cherries, apricots, peaches, nectarines, plums, etc) nut trees (almonds, walnuts, pecans, etc) roses, some caneberries (blackberry, boysenberry, youngberries, loganberries), euonymus, clematis, hops, kiwifruit, persimmons; and although lab studies show K1026 not directly lethal to many crown gall pathogens that infect apple and pear trees, some research results and anecdotal field evidence supports efficacy of K1026 in some cases probably due to its strong root competitive and colonisation ability, thus excluding pathogens from infection sites as well as possible affects from some or all of K1026 produced bacteriocins. In another example, raspberry crown gall isolates were found to be insensitive to the bacteriocins produced by K1026, however, there is also anecdotal evidence to support the use of NOGALL with K1026 against raspberries crown gall pathogens as experienced in one nursery in New York state, USA. Grapevine crown galls, caused by biovar 3 type pathogenic agrobacteria, are very different to other biovars of agrobacteria and are not at all controllable by K1026.
K1026 cells in NOGALL work against many crown gall pathogenic agrobacteria by various mechanisms such as:
1. their excellent ability to colonise roots, particularly root lenticels, and plant wound sites to exclude attachment of pathogenic agrobacteria;
2. competition for plant foods and attachment sites;
3. bacteriocin (antibacterial nucleosides or nucleotides) production by K1026 including agrocin 84, agrocin 434 and ALS84. Agrocin 84 mimics the plant foods (carbon compounds) produced by galls (opines called nopaline and agrocinopine A) so its accidental uptake by pathogenic agrobacteria via this trojan horse compound leads to inhibition of cellular leucyl-tRNA synthetases and AgnB2, a gene which confers immunity to the antibiotic. The inhibition of protein synthesis via the aminoacylation reactions, results in significant disruption to cellular functions and viability. Agrocin 84 is specific for agrocinopine-catabolising agrobacteria, most of which are crown gall pathogens, other organisms are unaffected.
Successful biocontrol of crown gall in the targeted crops depends on many factors, for example, use of disease-free stock, exposure of stock to pathogens prior to treatment of NOGALL, application method, post treatment storage of treated stock, exposure of NOGALL bacteria to toxic chemicals, presence and number of K1026 bacteriocin resistant pathogens, treatment of stock at every transfer stage, proper storage of NOGALL cultures prior to use, etc….(see also Q.19).
NOGALL should be applied as an aqueous dip solution made up by adding NOGALL peat culture to cool clean, non-chlorinated, drinking-quality water. Plant stock should be dipped into the solution within 2 hours at each propagation stage, e.g. seed, taking cuttings, lifting of stock and / or transferring stock. Seeds, cuttings or all roots, lower stems or any other parts where wounds may have occurred should be well saturated with the dip solution. NOGALL solution can also be sprayed on wounded tissue both on roots and above ground plant stems. Survival of K1026 on aerial parts will be poor due to detrimental effects of desiccation and sunlight. Separate spraying of aerial plant stems and leaves will not protect roots from infection by crown gall agrobacteria. Make sure the plant stock is thoroughly wetted with the NOGALL solution.
No, dilution reduces the bacterial cell count in the dip solution and could reduce efficacy. Fresh cultures of NOGALL contain greater than 1,000 million viable cells of K1026 per gram and when mixed with water provides a dip solution containing greater than 20 million viable K1026 cells per ml which has been proved effective. Less bacterial cells can reduce the colonisation of plant wounds and lead to insufficient production of the bacteriocins agrocin 84, 434 and ALS84, thus reducing protection against sensitive pathogenic agrobacteria.
No, over inoculation is not harmful to plants and does not impose a safety risk to humans, insects, birds, fish or other animals.
If the dip solution becomes very dirty, change to fresh solution. This will depend on how much soil is attached to propagation stock. As a general rule, replace the 12 litre treatment suspension after treating the equivalent of about 2,500 small bare-rooted seedlings or 200-500 bare-rooted small saplings or when the suspension becomes excessively dirty.
Once the dip solution is prepared, it is recommended to use it within 8 hours, but no longer than 24 hours. Dip solutions held longer can allow contaminant microorganisms resident in the water source, on the container or utensils to multiply in the dip solution from nutrients introduced with NOGALL peat cultures and these resident microorganisms could interfere with K1026 cell activity.
There is scientific evidence showing that the attachment of bacteria to susceptible plant cells happens within 15-30 minutes of application and total binding occurs by about 2 hours. There are three distinct stages that take place before irreversible polar cell attachment to cell sites as a result of expression of a suite of genes. Hence, it is particularly important to keep plant stock moist for 30 minutes or longer to help K1026 cells attach to wound infection sites and increase chance of biological control of crown gall. Pathogenic agrobacteria are capable of attachment and transfer of plasmid T-DNA from the bacteria to the host plant cell during a timeframe 4-8 hours post exposure.
There is no set formula for the amount of NOGALL needed to treat a set number of propagation stock. This will depend on a number of variables, such as the stem diameter of the plants, their root mass, cleanliness of the plant and method of application (i.e. spraying vs dipping). Although one can readily quantify the stem diameter and the number of the plants the other variables are more difficult to measure. The following can be used as a guide when using an 8.8 oz (250g) pack of NOGALL:
Australia and Turkey: A 12 litre dip solution (registered Australian application rate) made up from a 250g pack of NOGALL will treat up to 2,000-5,000 cuttings, or about 1,000-2,500 bare rooted seedlings with 4-6mm diameter stems, or about 200-500 bare rooted, small saplings with stem diameters of about 8-10mm, or up to 17 kg of seeds depending on seed size.
USA: A 2.5 gallon dip solution (registered US application rate) made up from a 250g pack of NOGALL should treat up to 2,000-5,000 cuttings, or about 1,000-2,500 bare-rooted seedlings with about ¼” stem diameters, or about 200-500 (with soft ball size root system) bare rooted small saplings, both depending on how much soil is attached to the root system, or up to 37.5 lb of seeds, depending on seed size.
Any method that protects NOGALL dip solution on plant material will increase the rate of colonisation and attachment of K1026 cells to plant wound cells. For example, plastic or hessian/burlap bags can be used to protect treated stock against sunlight, wind and desiccation following application of the inoculant.
NOGALL is formulated to deliver high numbers of viable cells of the active ingredient Rhizobium rhizogenes strain K1026. It is formulated in a neutralised, pre-sterilised, microfine peat medium containing suspending and adhesion agents to aid in plant attachment and to protect the cells after application to plant tissue. K1026 cells are better able to survive desiccation conditions on plant material because they have been grown-up in peat and formulated with additives.
The peat formulation also protects the inoculant bacteria during transport and storage of the product.
Inoculation of plant rootstock with NOGALL can add between 1-10 million bacteria per gram of fresh weight of root. This population can reduce to 10,000 to 100,000 after 15-20 weeks. NOGALL bacteria can survive for at least 2 years in a field environment as a rhizosphere inhabitant on treated stock or on weeds or grass roots, in soil or in association with crown gall tissue. Plant galls are genetically programmed to produce special food (opines) for uptake by agrobacteria; some non-disease agrobacteria can also utilise the secreted opines and other food compounds produced by the plant cells in the gall tissue. Hence, the existence of galls can lead to build up of populations of many different types of agrobacteria.
(Ref. 35)
Any nursery that buys in propagation stock from a source that has not used NOGALL risks purchasing diseased stock. Visible disease development usually takes 2 to 4 weeks after infection at soil temperatures of 68ºF (20ºC) or above. Development stops altogether at soil temperatures below 50ºF (10ºC). It is advisable to always specify treatment with NOGALL at each propagation stage. NOGALL treatment should be done immediately or within 2 hours after transferring or lifting plant stock, wounding or removal from cold storage. This minimises risk of disease contact and infection. Value adding by use of NOGALL should be promoted by nurseries. Treating plant wounds with NOGALL at each transfer stage is essential to protect against crown gall infection. If plant material is in contact with crown gall pathogenic agrobacteria prior to treatment with NOGALL, infections can occur and disease can develop. Wounded plant tissue offers infection sites for pathogenic agrobacteria and by saturating these infection sites with K1026 cells, it excludes and protects the plant from disease infection. Crown gall infections have been mostly associated with plant material where active plant cell division is occurring, such as wound areas, next to grafts, emerging lateral roots and lenticels that are accessible by pathogenic agrobacteria.
Even though plant stock was dipped 3 months prior to planting out NOGALL should be used again at the transfer stage from its growing medium to field planting as new wounds can occur during this transfer stage and offer new infection sites for pathogens in the field.
No, once a plant cell is infected with DNA from pathogenic agrobacteria, galling will occur and is then uncontrolled by strain K1026. In some cases the pathogenic agrobacteria can colonise the vascular tissue and cause galling in other parts of the plant where wounds are caused by wind or hail damage, insects such as borers, nematodes, grafting, cracks formed by developing lateral roots or root lenticels, frost or freeze injury and other causes. In these cases removing galled tissue would be ineffective against prevention of further galling. A list of plant stock that can have systemic infection is not available but walnuts, almonds, roses, cherries, pears, apples and grapevines are known to have pathogenic agrobacteria present in vascular tissue.
(per. comm. L. Moore).
Cuttings must be dipped before placing in a sawdust medium. When planting out they should be dipped again as new wounds could be caused by the transfer. Pathogens can be found in soil, water and on utensils that have come into contact with them. Sawdust can also contain disease-causing agrobacteria.
The risk of crown gall infection can be reduced by:
- Using disease-free plant stock;
- Choosing rootstock that is known to be less susceptible to crown gall;
- Removing and destroying galled plants (e.g. burning) as soon as possible;
- Using aseptic techniques such as disinfecting pruning and propagation equipment frequently, for example, implements used when grafting, taking cuttings or root pruning, sterilising soil potting mixes, avoiding soil or water that may contain crown gall pathogens;
- Not planting seedlings too deeply;
- Avoiding soils which are heavily infested with nematodes or root attacking insects;
- Avoiding clay soils which are subject to water-logging or poor drainage;
- Avoiding unnecessary damage to roots and cuttings during planting or cultivation;
- Keeping grafts and buds above soil line;
- Solarise lighter soils where infestations are known;
- Irrigate with well water or sanitised pond water;
- Minimise risk of frost and freeze damage;
- Avoiding fields with recent history of high crown gall infestations.
Some yes, some no. The following list should be used as a general guide only as different methods of application can have different effects on the viability and effectiveness of the inoculant bacteria in NOGALL.
| Yes
Benomyl (Benlate®) Methyl thiophanate (Topsin®) Mefenoxam (Ridomil®) |
No
Captan |
Treat NOGALL first, then dip in non-alcohol powder based hormones or Previcur® and then plant. For alcohol or water based hormone solutions treat cuttings first with hormone, allow alcohol and/or water to evaporate, then treat with NOGALL and then plant.
(per. comm. A. Kerr)
Crown gall disease caused by pathogenic agrobacteria can spread by splashing rain, cultivation, contaminated utensils, soil and water. Bacteria can be spread in soil by water transport or along developing roots such as on weeds and grasses. Galls can contain 1-10 million pathogenic agrobacteria per gram of tissue and root rhizosphere counts have been recorded between 10,000 to 1 million per gram of root tissue of cherry, ryegrass and 11 other herbaceous plants. Soil can frequently contain 500 or more cells per gram, however, most agrobacteria are found in the rhizosphere along roots and in crown gall tissue. Damage to roots of field grown nursery stock from cultivation should be avoided as this creates new infection sites and leads to a build up of galls and pathogenic agrobacteria in the field.
Populations of pathogenic agrobacteria can survive for years as soil inhabiting bacteria, rhizosphere inhabitant or in association with crown gall tissue. Generally, populations slowly decline in fallow soil and in water. In one study, agrobacteria soil populations of 100,000 per gram of dry soil declined to about 100 per gram after 8 weeks and less than 100 after 16 weeks. Higher populations are generally more prevalent in heavy clay soils or in soils where water can stand for several days. K1026 inoculated peach x almond seedlings planted in infested soil colonised to a level of one million cells per gram of root at 8 months post treatment while pathogenic agrobacteria levels were 100 to one million per gram of root.
Drenching the soil around a tree with NOGALL solution will increase populations of K1026 temporarily and may lead to increased colonisation of the root rhizophere. This would aid in the protection against crown gall infection but no studies have been done on its field effectiveness against crown gall disease. Drenching is appropriate for potted plants and for seedlings or cuttings in cell trays.
It is recommended to avoid soil or fields with a history of crown gall. The risk of future infections will be increased if frequent root damage occurs due to cultivation, nemotodes, soil larvae, wind damage or other means. When field planting stock that is susceptible to crown gall ensure all trees are treated with NOGALL just before planting.
- NOGALL is an easy to use formulation;
- NOGALL is a robust product and can be out of refrigeration during transport without loss of quality;
- NOGALL has a long shelf life of 6 months when stored at 2-5º C (35-40 ºF);
- When using K84 there is risk of transfer, via conjugation, to pathogenic agrobacteria of the agrocin 84 producing plasmid (pAgK84) and subsequent loss of agrocin 84 sensitivity and, hence, ultimate loss of effectiveness of K84. The agrocin 84 producing plasmid in K1026 (pAgK1026) cannot transfer to pathogenic agrobacteria, hence ensuring the long term effectiveness of this unique biological control agent.
This phenomenon has been observed in field and laboratory trials in Greece, USA, Spain and Italy. The breakdown of biological control is caused by K84’s ability to conjugate with pathogenic agrobacteria and transfer its’ agrocin 84 producing plasmid (pAgK84) into the cell of pathogenic agrobacteria. This results in a pathogen that can produce agrocin 84 as well as acquiring immunity to this bacteriocin. This conjugation problem can lead to a build-up of uncontrollable, agrocin 84 insensitive pathogens. K1026 cannot transfer its’ agrocin 84 producing plasmid (pAgK1026) to pathogenic agrobacteria so it’s use protects against this breakdown possibility and ensures the long-term value of K1026 for the biological control of crown gall disease in the targeted host crops.
Only sell stock to growers if they will use it within the expiry period. Sales of NOGALL outside the labelled expiry date may lead to reduced efficacy due to lower numbers of viable cells of K1026 in the product and then legal issues may arise if efficacy is in doubt. Outdated NOGALL cultures can be watered into plant stock or disposed of in an authorised landfill.
NOGALL is very safe for humans, insects, birds, fish and plants. Label precautions use generic statements for use with any bacterial inoculant product and are intended to safeguard misuse and unnecessary exposure of foreign bacteria to eyes, skin and ingestion. Contact with eyes could cause minor irritation.
Grapevines can have resident pathogenic agrobacteris on their roots, stems, leaves, buds, or even within the plant vascular system. Grapevine tissue colonised by these crown gall-causing bacteria are genetically quite different to other pathogenic agrobacteria and are not sensitive to the bacteriocins produced by K1026. These pathogens are a distinct group (biovar 3) of agrobacteria specific to grapevines. Hence, root, stem or graft applications of K1026 on grapevine stock will not control infection or development of crown gall disease.
(Ref: 33)
Studies on the types of crown gall pathogenic agrobacteria that infect apples and pears indicate that many are insensitive to the bacteriocins produced by K1026. However, there are some published reports of successful crown gall control in laboratory and field plantings, probably due to the strong colonising and competitive ability of K1026 resulting from their high populations applied from the inoculant treatments. Successful control of crown gall in apples and pears using NOGALL with K1026 has also been reported as anecdotal evidence from some growers over the years. However, the general higher risk of crown gall infection and, in some cases, questionable efficacy of K1026 against some of these bacteriocin insensitive agrobacteria, necessitates its exclusion in our recommended host range.